Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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FXUS62 KRAH 261633

Area Forecast Discussion
National Weather Service Raleigh NC
1230 PM EDT Wed Jul 26 2017

A surface front will stall over SC through this afternoon, then
retreat north through NC as a warm front later tonight and Thu.


As of 1020 AM Wednesday...

Little change to the near term forecast.

12Z upper air analysis depicts a weak, narrow ridge of sfc high
pressure nosing southwestward across central NC. This weather system
has helped to shunt a stalled sfc front well south into SC. Low
level ely flow around this high has resulted in a with the boundary
n upslope component across western NC. This flow has aided in the
development of a deck of stratus which has spread east into the
western fringe of the western Piedmont. In our region, this deck of
clouds is more prominent across sections of the Triad. As the day
wears on, mixing of drier air from aloft will aid to gradually erode
this cloud deck, yielding mostly-partly sunny skies this afternoon.

The low level easterly flow will maintain a slightly cooler than
normal air mass over central NC. Afternoon temperatures in the mid-
upper 80s anticipated. With dewpoints generally in the low-mid 60s,
it should feel tolerable for late July.

Convective chances still appear minimal, though a stray shower or
storm cannot be ruled out across the southern Piedmont where the
atmosphere will be a tad wetter/better instability compared to the
rest of the region.


As of 215 AM Wednesday...

High pressure aloft over south-central U.S. will try to ridge
eastward into the region, however an upper low over GA/FL and the
amplifying trough over the Northeast will largely inhibit it. The
previous surface front will have fully retreated northward and
eastward out of the region, with warm, moist southerly flow and a
lee-trough taking it`s place over the region. The next frontal
system out west will continue to approach and impinge on the area
through Thursday night. As a result, much of the day Thursday should
be dry, however there will be increasing clouds and chances for
convection through the overnight period. Best chances for showers
and storms overnight should be restricted to the north and
northwest. Expect highs in the upper 80s NW to low 90s south and
overnight lows again returning to the low to mid 70s.

&& The temperature & dew point sensor at site KFAY, located at the
Fayetteville Regional Airport, is malfunctioning. NWS technicians
have turned the sensor off and ordered parts to repair it. At this
time, we expect the sensor to be returned to service early next week.

As of 430 AM Wednesday...

A vigorous mid-level shortwave trough/compact upper low will dive
SEWD through the Ohio Valley on Friday, and then through the  the
Mid-Atlantic region Friday night and into the day on Saturday before
moving off the Mid-Atlantic Coast Saturday evening/night.

A surface low will undergo modest deepening over the northern Mid-
Atlantic states as it comes under the increasing influence of the
strong 80 to 100 meter synoptic scale height falls attendant to the
digging mid-level trough. As the surface low shifts off the Mid-
Atlantic Coast late Friday night, it will drag a cold front SE
through the area late Friday night.

There remains much uncertainty with the evolution (timing/location)
of strong to severe convection across central NC, particularly given
the potential for lead shortwave energy/disturbances ejecting east
well ahead of the primary shortwave trough to support upstream
convection/MCS into the region as early as Thursday night/Friday
morning and the subsequent effects on heating/destabilization across
the area later Friday afternoon. For now, will carry chance pops
Friday through the first half of the day on Friday, increasing to
likely pops Friday afternoon and into the evening with the arrival
of the better forcing. If sufficient instability can develop,
strengthening low-level kinematic winds in the 925-850mb layer of 30-
35kts could support a threat for severe storms across the area
Friday afternoon and evening, with damaging straight-line winds the
greatest threat. Stay tuned.

Can`t rule out an isolated shower across the area on Saturday as the
upper trough/vort max swings through the area. Otherwise skies will
be clearing with a noticeably cooler and drier airmass in place
through the weekend. Highs Saturday through Monday will top out
mostly in the mid 80s...3-5 degrees below normal, with morning lows
in the mid to upper 60s. The front, meanwhile, will be stalled along
the coast, with potential for development of a surface low along the
front that could pull moisture back into at least the eastern
sections of the state by midweek.


As of 1230 PM Wednesday...

An area of high pressure extending across central NC this afternoon
will provide VFR conditions through Thursday. The exception will be
pockets of MVFR/IFR visibility due to fog overnight tonight through
daybreak Thursday or patches of MVFR ceilings. The fog appears most
probable in vicinity of of KFAY and KRWI between 09Z-12Z Thu.

While VFR parameters anticipated for much of Thursday, an
approaching cold front will increase the risk of scattered
convection across the northern counties late Thursday but more so
Thursday night. At this time, it appears scattered convection may be
in the vicinity of the Triad terminals and KRDU after 02Z Friday,
persisting into Friday morning.

Additional scattered convection and associated MVFR parameters
appear probable across central NC Friday through Friday night as the
sfc cold front drifts southward. A drier, more stable atmosphere and
attendant VFR parameters expected Saturday through Monday.


Technicians have completed the bulk of the first phase of the
Service Life Extension Project (SLEP) upgrade and the data
quality is sufficient for the radar to return to service.
Additional radar adjustments resulting in brief outages are
still possible through Thursday.




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